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This article is devoted to further development of the generalized van der Waals theory and its application to non-uniform hard sphere fluids. A coarse-graining assumption included in the original derivation is replaced by a weaker assumption recognizing the non-zero range of hard core interactions. The new fine-grained theory thus contains a non-local entropy functional and allows fluid structure on a length scale shorter than the hard core diameter to be resolved. Moreover, it contains a simplified representation of the mechanism leading to hard sphere structure due essentially to geometrical packing constraints. This is shown by application of the theory to hard sphere adsorption profiles in the case of a hard wall and to radial distribution functions of a hard sphere fluid. The amount of structure is underestimated partly due to the use of a density-independent excluded volume. It is shown that this flaw can be remedied by use of a hard- sphere entropy functional which successfully interpolates between the original high density estimate and the known behaviour in the low density limit.

The role of intermolecular forces in the phase behaviour of mixtures of dipolar hard spheres is investigated by using the mean spherical approximation of statistical mechanics. This approach yields an analytical expression for the dipolar contribution to the internal energy which is numerically integrated to obtain the Helmholtz free energy. These results are then used to obtain the dipolar contribution to the 'energy pressure' and the Gibbs free energy. The double tangent construction gives details of the composition of fluid phases in equilibrium. The composition-temperature curves exhibit liquid-liquid and liquid-fluid immiscibilities for three selected molecular systems in which only the diameter of one species varies, while the rest of the potential parameters are held constant.